CN102701148A

CN102701148A - Method and device for combined production of ammonia synthesis gas and SNG by fixed bed crushed coal pressurization and gasification

Info

Publication number: CN102701148A
Application number: CN2011102432909A
Authority: CN
Inventors: 杨震东; 支红利; 陈晏
Original assignee: SHANGHAI INTERNATIONAL CONSTRUCTION ENGINEERING CONSULTING CO LTD
Current assignee: SHANGHAI INTERNATIONAL CONSTRUCTION ENGINEERING CONSULTING CO LTD
Priority date: 2011-08-23
Filing date: 2011-08-23
Publication date: 2012-10-03
Anticipated expiration: 2031-08-23
Also published as: CN102701148B

Abstract

The invention discloses a method for combined production of ammonia synthesis gas and SNG by fixed bed crushed coal pressurization and gasification; raw coal gas is subject to a CO shift step, a low-temperature methanol washing step, and a liquid nitrogen washing step, and then is delivered to an ammonia synthetic step for ammonia synthesis, and a by product of SNG is obtained in the liquid nitrogen washing step. The method omits a complicated methane conversion working section in a traditional synthesis gas production process by using a liquid nitrogen washing device and low-temperature separation technology; inert gas in the synthesis gas is removed, and the methane fraction is separated into liquid methane; finally the synthesis gas is reheated and flows out of a cold box, and reaches the specification for artificial natural gas (SNG) as clean energy. In addition, raw material gas is subject to purification and methane separation, which not only reduces the influence of inert gas in a synthetic loop, reduces waste gas discharge, but also causes no addition of additional mobile equipment, realizes combined production of synthetic ammonia and SNG, and has significant economic and social benefits. The invention also discloses a device used in the method.

Description

Fixed bed broken coal pressing gas system ammonia synthesis gas and SNG co-production and device

Technical field

The present invention relates to synthetic ammonia gas purification technique field; Especially produce synthetic ammonia and the artificial Sweet natural gas technical field of by-product SNG (Substitute Natural Gas) to a kind of synthetic gas of BGL (British Gas-Lurgi) broken coal slag pressurized-gasification furnace and Lu Qi (Lurgi) crushed coal pressurized-gasification furnace that utilizes; Be particularly related to a kind of with low temperature liquid nitrogen as absorption agent; Remove CO in the mixed gas, Ar, CH4; And in this treating processes, be that fixed bed broken coal pressing gas system ammonia synthesis gas and the SNG co-production and the device of the artificial gas product of SNG (Substitute Natural Gas), this method and device are applicable to that synthetic gas (hydrogen, carbon monoxide, nitrogen, methane, argon) purification makes the less energy-consumption new type low temperature liquid nitrogen washing (gas removal) and the SNG co-production technology in synthetic ammonia field with isolated methane fraction is refining.

Background technology

At present, the BGL of many coal chemical industry enterprises or the virgin gas after the Lurgi gasification, basal component also has part methane except that carbon monoxide, hydrogen.In the synthetic ammonia process of producing product, need to remove through the liquid nitrogen washing operation rare gas element such as methane or to the deleterious gas of catalyzer, get back to the liquid nitrogen washing operation again after the methane rich cut being delivered to workshop section such as methane conversion again, Zhongdao synthesis procedure is produced ammonia.

Synthetic ammonia process based on BGL or Lurgi stove has constituted a loop chain during the course like this; This chain is as shown in Figure 1; Raw gas that its BGL or Lurgi stove are come is removed rare gas element such as methane or to being sent to synthesis procedure production ammonia behind the deleterious gas of catalyzer with the liquid nitrogen washing operation through low-temperature rectisol, the methane rich cut of liquid nitrogen washing operation is got back to the liquid nitrogen washing operation again after delivering to workshop section such as methane conversion.This flow process exists following not enough: 1, this process energy consumption is high, the waste resource; 2, the variable effect methane conversion workshop section of the CH4 cut of liquid nitrogen washing workshop section; 3, long flow path, the degree of coupling is high, influence the stablizing of factory, safety, LP reliability service; 4, the concentration of methane is low in low, the methane fraction of methane recovery, calorific value is little; 5, product simplification.

In order to open loop chain, improve the calorific value and the recovery of methane, can be the product of SNG specification with the methane fraction in the liquid nitrogen washing process is refining, will help the steady running of synthetic ammonia installation.

SNG is the clean energy that develops rapidly in recent years, have pollution-free, calorific value is high.Along with the development of society, the progress and the human consciousness enhancing of science and technology to environment protection; In recent years; SNG receives much concern as clean energy; And have and much mention the patent that BGL or Lurgi vapourizing furnace are produced SNG, these patents only are to produce SNG, do not break the simplification problem of BGL or Lurgi vapourizing furnace the finished product.

With BGL or Lurgi vapourizing furnace is gasification process, and can produce synthetic ammonia and SNG simultaneously will be a brand-new problem, can realize the coproduction of synthetic ammonia and SNG, and the key problem of this coproduction is to realize gas cleaning and separate like how lower energy consumption.

Summary of the invention

One of technical problem to be solved by this invention is to the existing in prior technology problem a kind of fixed bed broken coal pressing gas system ammonia synthesis gas and SNG co-production to be provided; This method is through liquid nitrogen washing device and low ternperature separation process technology; Save the methane conversion workshop section of complex procedures in traditional synthetic gas production process, in removing synthetic gas, in the indifferent gas, methane fraction has been separated into liquid methane; Last re-heat cooling box can be used as the artificial Sweet natural gas (SNG) of clean energy.And virgin gas both reduced the influence of synthesis loop indifferent gas through purifying and methane separation, reduced discharge amount of exhaust gas, do not increase extra moving equipment again, realized synthetic ammonia and SNG coproduction, had remarkable economical and social benefit.

Two of technical problem to be solved by this invention is to provide said fixing bed broken coal pressing gas system ammonia synthesis gas and the employed device of SNG co-production.

Fixed bed broken coal pressing gas system ammonia synthesis gas and SNG co-production as first aspect present invention; After its raw gas process CO shift step, low-temperature rectisol step, the liquid nitrogen washing step; Send into synthetic ammonia step synthetic ammonia, it is characterized in that, tell SNG in said liquid nitrogen washing step.

In a preferred embodiment of the invention; Said liquid nitrogen washing step comprises that cooling step, methane separation step, nitrogen washes step, methane rectification step, gas-liquid separation step; The virgin gas of being come by the low-temperature rectisol step is after said cooling step heat exchange; Send into said methane separation step and carry out the methane fraction separation, the virgin gas A behind the said methane separation step separation of methane cut sends into nitrogen and washes step, and the isolating methane fraction of methane separation step is sent into the methane rectification step and carried out rectifying; The middle pressure nitrogen that gets into the liquid nitrogen washing step forms liquid nitrogen and sends into nitrogen and wash step after said cooling step heat exchange; With send into nitrogen and wash the virgin gas A counter current contact of step; And carry out mass transfer, heat transfer; CO among the virgin gas A, CH4, Ar impurity are dissolved in the liquid nitrogen from vapor condensation; The nitrogen gas washing that contains small amount of nitrogen that said nitrogen is washed after the step purge is sent into said cooling step; Said nitrogen is washed step cut that comes out and the gas B entering gas-liquid separation step of being come out by said methane rectification step and is carried out gas-liquid separation; Said gas-liquid separation step gas separated C and liquid B are sent into said cooling step respectively; The liquid A that said methane rectification step is come out is sent into said cooling step, send into nitrogen gas washing, gas C, liquid A, the liquid B of said cooling step and send into the virgin gas in the cooling step, middle pressure nitrogen carries out heat exchange, form synthetic gas after wherein said nitrogen is washed the nitrogen gas washing that contains small amount of nitrogen after the step purge and in said cooling step, joined nitrogen and send into the synthetic ammonia step; The liquid A that said methane rectification step is come out is seen off through forming SNG after the heat exchange, and said gas-liquid separation step gas separated C and liquid B are mixed after heat exchange formation fuel gas is seen off at said cooling step.

In a preferred embodiment of the invention; Said cooling step is divided into first cooling step, second cooling step, the 3rd cooling step; The middle pressure nitrogen of said entering liquid nitrogen washing step is sent into nitrogen through formation liquid nitrogen after first cooling step, second cooling step, the 3rd cooling step heat exchange successively and is washed step; Said virgin gas of being come by the low-temperature rectisol step is sent into said methane separation step and is carried out the methane fraction separation successively through after second cooling step, the 3rd cooling step heat exchange; The nitrogen gas washing that contains small amount of nitrogen that said nitrogen is washed after the step purge is sent into the 3rd cooling step behind the nitrogen and is carried out heat exchange through joining for the first time; Send into second cooling step again through the nitrogen gas washing after the 3rd cooling step heat exchange and carry out heat exchange formation crude synthesis gas; Crude synthesis gas after the second cooling step heat exchange is divided into two strands; Wherein first strand of crude synthesis gas sent into first cooling step and carried out heat exchange; Form the crude synthesis gas of normal temperature; Second strand of crude synthesis gas send the low-temperature rectisol step to return the cold that is brought from the low-temperature rectisol step by Purge gas, and the crude synthesis gas of the normal temperature that comes out with first cooling step after returning converges through accurate adjustment formation synthetic gas sends into synthetic ammonia step synthetic ammonia; The liquid A that said methane rectification step is come out is seen off through the SNG that forms normal temperature after the 3rd cooling step, second cooling step, the first cooling step heat exchange successively; After said gas-liquid separation step gas separated C and liquid B are mixed in the 3rd cooling step, see off through the fuel gas that forms normal temperature after second cooling step, the first cooling step heat exchange successively again.

In a preferred embodiment of the invention, send into second cooling step behind the nitrogen again and carry out heat exchange and form crude synthesis gas through joining for the second time through the nitrogen gas washing after the 3rd cooling step heat exchange.

In a preferred embodiment of the invention; Said nitrogen is washed the nitrogen gas washing that contains small amount of nitrogen after the step purge and is joined the liquid nitrogen that the nitrogenous source of nitrogen is hung oneself and come out after the 3rd cooling step heat exchange for the first time, and said nitrogen is washed the nitrogen gas washing that contains small amount of nitrogen after the step purge and joined the middle pressure nitrogen that nitrogen is hung oneself and come out after the second cooling step heat exchange for the second time.

In a preferred embodiment of the invention, in said gas-liquid separation step, also replenish liquid nitrogen.

The nitrogenous source of in a preferred embodiment of the invention, joining nitrogen the said first time adopts the isenthalpic throttling mode to allocate in the nitrogen gas washing that contains small amount of nitrogen after said nitrogen is washed step purge.

The nitrogenous source of in a preferred embodiment of the invention, joining nitrogen the said second time adopts the isenthalpic throttling mode to allocate in the nitrogen gas washing that contains small amount of nitrogen after said nitrogen is washed step purge.

Fixed bed broken coal pressing gas system ammonia synthesis gas and the employed device of SNG co-production as second aspect present invention; Comprise CO changing device, low temperature washing device for methanol, liquid nitrogen washing device, synthetic ammonia installation; Its raw gas is successively through seeing ammonia off behind CO changing device, low temperature washing device for methanol, liquid nitrogen washing device, the synthetic ammonia installation; It is characterized in that, in said liquid nitrogen washing device, be provided with the SNG outlet.

In a preferred embodiment of the invention, said liquid nitrogen washing device comprises the first unstripped gas water cooler, the second unstripped gas water cooler, the 3rd unstripped gas water cooler, nitrogen wash column, separating tank, flash tank, methane rectifying tower, gas liquid mixer, gas gas mixing tank; The middle pressure nitrogen inlet of the said first unstripped gas water cooler connects the empty middle pressure nitrogen that divides through first pipeline; The middle pressure nitrogen outlet of the first unstripped gas water cooler connects the middle pressure nitrogen inlet of the said second unstripped gas water cooler through second pipeline; The middle pressure nitrogen outlet of the said second unstripped gas water cooler connects the middle pressure nitrogen inlet of said the 3rd unstripped gas water cooler through the 3rd pipeline, and the liquid nitrogen outlet of the 3rd unstripped gas water cooler is connected to the liquid nitrogen inlet on said nitrogen wash column top through the 4th pipeline; The virgin gas inlet of the said second unstripped gas water cooler is connected to the virgin gas outlet of said low temperature washing device for methanol through the 5th pipeline; The virgin gas outlet of the second unstripped gas water cooler enters the mouth through the virgin gas that the 6th pipeline is connected to said the 3rd unstripped gas water cooler, and the virgin gas outlet of the 3rd unstripped gas water cooler is connected to the virgin gas inlet on the separating tank sidewall through the 7th pipeline; The top of said separating tank is provided with the virgin gas outlet behind the separation of methane cut; The bottom of separating tank is provided with the methane fraction liquid exit; Virgin gas outlet behind the said separation of methane cut enters the mouth through the virgin gas that the 8th pipeline is connected to said nitrogen wash column bottom, and said methane fraction liquid exit is connected to the methane fraction inlet of said methane rectifying tower bottom through the 9th pipeline; The top of said nitrogen wash column is provided with the outlet of nitrogen gas washing, and the bottom of nitrogen wash column is provided with the cut liquid exit; The top of said methane rectifying tower is provided with pneumatic outlet, and the bottom of methane rectifying tower is provided with the SNG liquid exit; Said nitrogen gas washing outlet is connected to the inlet of said gas liquid mixer through the tenth pipe; The outlet of said gas liquid mixer is connected to the nitrogen gas washing inlet of the 3rd unstripped gas water cooler; Said gas liquid mixer is provided with first and joins the nitrogen mouth, and said first joins the nitrogen mouth is connected to said the 4th pipeline through the 11 pipeline and first throttle valve; The nitrogen gas washing outlet of the 3rd unstripped gas water cooler is connected to the inlet of said gas gas mixing tank; The outlet of gas gas mixing tank is connected to the nitrogen gas washing inlet of the said second unstripped gas water cooler through the 12 pipeline; Said gas gas mixing tank is provided with second and joins the nitrogen mouth, and said second joins the nitrogen mouth is connected to said the 3rd pipeline through the 13 pipeline and second throttling valve; The nitrogen gas washing outlet of the said second unstripped gas water cooler connects the cold synthetic gas inlet in the said low temperature washing device for methanol through the 14 pipeline on the one hand; The nitrogen gas washing outlet of the second unstripped gas water cooler connects the synthetic gas inlet of the said first unstripped gas water cooler on the other hand through the 15 pipeline; The syngas outlet of the first unstripped gas water cooler enters the mouth through the hot synthesis gas that the 16 pipeline is bonded into ammonia device, and the hot synthesis gas outlet in the said low temperature washing device for methanol connects the 16 pipeline; The cut liquid exit of said nitrogen wash column bottom is connected to the cut liquid inlet on the said flash tank through the 17 pipeline, and the pneumatic outlet at said methane rectifying tower top connects the gas inlet on the said flash tank through the 18 pipeline; The top of said flash tank is provided with pneumatic outlet; The bottom of flash tank is provided with liquid exit; The pneumatic outlet of said flash drum overhead is connected to the fuel gas inlet of said the 3rd unstripped gas water cooler through the 19 pipeline; The liquid exit of flash tank bottom is connected to the fuel gas inlet of said the 3rd unstripped gas water cooler through the 20 pipeline; The fuel gas outlet of said the 3rd unstripped gas water cooler is connected to the fuel gas inlet of the said second unstripped gas water cooler through the 21 pipeline; The fuel gas outlet of the second unstripped gas water cooler enters the mouth through the fuel gas that the 22 pipeline is connected to the said first unstripped gas water cooler, and the fuel gas outlet of the first unstripped gas water cooler is connected to the fuel gas storage tank through the 23 pipeline; The SNG liquid exit of said methane rectifier bottoms is connected to the SNG inlet of said the 3rd unstripped gas water cooler through the 24 pipeline; The SNG outlet of the 3rd unstripped gas water cooler is connected to the SNG inlet of the said second unstripped gas water cooler through the 25 pipeline; The SNG outlet of the second unstripped gas water cooler is connected to the SNG inlet of the said first unstripped gas water cooler through the 26 pipeline; SNG outlet in the said liquid nitrogen washing device of the SNG export mixes of the first unstripped gas water cooler, the SNG outlet of this first unstripped gas water cooler is connected to the SNG storage tank through the 27 pipeline.

In a preferred embodiment of the invention, said liquid nitrogen washing device comprises the first unstripped gas water cooler, the second unstripped gas water cooler, the 3rd unstripped gas water cooler, nitrogen wash column, separating tank, flash tank, methane rectifying tower, gas liquid mixer; The middle pressure nitrogen inlet of the said first unstripped gas water cooler connects the empty middle pressure nitrogen that divides through first pipeline; The middle pressure nitrogen outlet of the first unstripped gas water cooler connects the middle pressure nitrogen inlet of the said second unstripped gas water cooler through second pipeline; The middle pressure nitrogen outlet of the said second unstripped gas water cooler connects the middle pressure nitrogen inlet of said the 3rd unstripped gas water cooler through the 3rd pipeline, and the liquid nitrogen outlet of the 3rd unstripped gas water cooler is connected to the liquid nitrogen inlet on said nitrogen wash column top through the 4th pipeline; The virgin gas inlet of the said second unstripped gas water cooler is connected to the virgin gas outlet of said low temperature washing device for methanol through the 5th pipeline; The virgin gas outlet of the second unstripped gas water cooler enters the mouth through the virgin gas that the 6th pipeline is connected to said the 3rd unstripped gas water cooler, and the virgin gas outlet of the 3rd unstripped gas water cooler is connected to the virgin gas inlet on the separating tank sidewall through the 7th pipeline; The top of said separating tank is provided with the virgin gas outlet behind the separation of methane cut; The bottom of separating tank is provided with the methane fraction liquid exit; Virgin gas outlet behind the said separation of methane cut enters the mouth through the virgin gas that the 8th pipeline is connected to said nitrogen wash column bottom, and said methane fraction liquid exit is connected to the methane fraction inlet of said methane rectifying tower bottom through the 9th pipeline; The top of said nitrogen wash column is provided with the outlet of nitrogen gas washing, and the bottom of nitrogen wash column is provided with the cut liquid exit; The top of said methane rectifying tower is provided with pneumatic outlet, and the bottom of methane rectifying tower is provided with the SNG liquid exit; Said nitrogen gas washing outlet is connected to the inlet of said gas liquid mixer through the tenth pipe; The outlet of said gas liquid mixer is connected to the nitrogen gas washing inlet of the 3rd unstripped gas water cooler; On said gas liquid mixer, also be provided with first and join the nitrogen mouth, said first joins the nitrogen mouth is connected to said the 4th pipeline through the 11 pipeline and first throttle valve; The nitrogen gas washing outlet of the 3rd unstripped gas water cooler is connected to the nitrogen gas washing inlet of the said second unstripped gas water cooler through the 12 pipeline; The inlet of said gas gas mixing tank, the outlet of gas gas mixing tank also is provided with second and joins the nitrogen mouth on said gas gas mixing tank, and said second joins the nitrogen mouth is connected to said the 3rd pipeline through the 13 pipeline and second throttling valve; The nitrogen gas washing outlet of the said second unstripped gas water cooler connects the cold synthetic gas inlet in the said low temperature washing device for methanol through the 14 pipeline on the one hand; The nitrogen gas washing outlet of the second unstripped gas water cooler connects the synthetic gas inlet of the said first unstripped gas water cooler on the other hand through the 15 pipeline; The syngas outlet of the first unstripped gas water cooler enters the mouth through the hot synthesis gas that the 16 pipeline is bonded into ammonia device, and the hot synthesis gas outlet in the said low temperature washing device for methanol connects the 16 pipeline; The cut liquid exit of said nitrogen wash column bottom is connected to the cut liquid inlet on the said flash tank through the 17 pipeline, and the pneumatic outlet at said methane rectifying tower top connects the gas inlet on the said flash tank through the 18 pipeline; The top of said flash tank is provided with pneumatic outlet; The bottom of flash tank is provided with liquid exit; The sidepiece of flash tank is provided with the liquid nitrogen inlet; The liquid nitrogen inlet of said flash tank sidepiece is connected to the 4th pipeline through the 24 pipeline; The pneumatic outlet of said flash drum overhead is connected to the fuel gas inlet of said the 3rd unstripped gas water cooler through the 19 pipeline; The liquid exit of flash tank bottom is connected to the fuel gas inlet of said the 3rd unstripped gas water cooler through the 20 pipeline; The fuel gas outlet of said the 3rd unstripped gas water cooler enters the mouth through the fuel gas that the 21 pipeline is connected to the said second unstripped gas water cooler, and the fuel gas outlet of the second unstripped gas water cooler enters the mouth through the fuel gas that the 22 pipeline is connected to the said first unstripped gas water cooler, and the fuel gas outlet of the first unstripped gas water cooler is connected to the fuel gas storage tank through the 23 pipeline; The SNG liquid exit of said methane rectifier bottoms is connected to the SNG inlet of said the 3rd unstripped gas water cooler through the 24 pipeline; The SNG outlet of the 3rd unstripped gas water cooler is connected to the SNG inlet of the said second unstripped gas water cooler through the 25 pipeline; The SNG outlet of the second unstripped gas water cooler is connected to the SNG inlet of the said first unstripped gas water cooler through the 26 pipeline; SNG outlet in the said liquid nitrogen washing device of the SNG export mixes of the first unstripped gas water cooler, the SNG outlet of this first unstripped gas water cooler is connected to the SNG storage tank through the 27 pipeline.

In a preferred embodiment of the invention, be provided with reboiler at the bottom of the tower of said methane rectifying tower, the inlet of said reboiler connects the 3rd or the 6th pipeline, and the outlet of reboiler takes back the 3rd pipeline or the 6th pipeline.

Owing to adopted technique scheme, liquid nitrogen washing step of the present invention mainly is made up of following four streamlines:

(a) purified gas streamline

The virgin gas that comes out from low-temperature rectisol step molecular sieve gets into the liquid nitrogen washing step through the 5th pipeline; In the second unstripped gas water cooler and the 3rd unstripped gas water cooler, carry out heat exchange with the synthetic gas, fuel gas and the methane rich cut (SNG) that backflow; After using virgin gas temperature behind the 3rd unstripped gas water cooler and reducing; Getting into separating tank through the 7th pipeline separates the methane fraction in the virgin gas; Virgin gas behind the separation of methane cut is exported out by the virgin gas at separating tank top, gets into the bottom of nitrogen wash column through the 8th pipeline.In nitrogen wash column, the virgin gas of rising becomes counter current contact with the liquid nitrogen that nitrogen wash column top is come, and carries out mass transfer, heat transfer.Impurity such as CO, CH4, Ar are dissolved in the liquid nitrogen from vapor condensation; The nitrogen gas washing that contains small amount of nitrogen after the purification leaves nitrogen wash column by the cat head of nitrogen wash column, gets into gas liquid mixer through the tenth pipeline, mixes with hydraulic fluid nitrogen in the part of sending into gas liquid mixer through the 11 pipeline; After making H2/N2 reach 3 (volume ratios) approximately; Form crude synthesis gas, successively crude synthesis gas is sent into the 3rd unstripped gas water cooler, the second unstripped gas water cooler again, in the 3rd unstripped gas water cooler and the second unstripped gas water cooler; After the logistics heat exchange such as crude synthesis gas and virgin gas, middle pressure nitrogen; Be divided into two strands of crude synthesis gas after going out the second unstripped gas water cooler, one crude synthesis gas gets into the first unstripped gas water cooler through the 15 pipeline, in fuel gas, SNG cool off, presses nitrogen; After going out the first unstripped gas water cooler, crude synthesis gas, fuel gas, SNG etc. are all by re-heat to normal temperature; Another strand crude synthesis gas send the low-temperature rectisol step to return the cold that is brought from the low-temperature rectisol step by virgin gas; Returning the back converges with the crude synthesis gas that the first unstripped gas water cooler comes out; After accurate adjustment, be H2/N2 that 3 synthetic gas is sent into ammonia synthesis step synthetic ammonia.

Get into through the tenth pipeline perhaps that hydraulic fluid nitrogen mixes in the nitrogen gas washing that contains small amount of nitrogen and the part of sending into gas liquid mixer through the 11 pipeline after the purification of gas liquid mixer; Incorporate hydraulic fluid nitrogen in the part into, send into the 3rd unstripped gas water cooler heat exchange again, go out the 3rd unstripped gas water cooler after; Send into gas gas mixing tank; Mix with the middle pressure nitrogen of bringing through the 13 pipeline, make H2/N2 reach 3 (volume ratios) approximately, the nitrogen gas washing of joining behind the nitrogen is called crude synthesis gas.Crude synthesis gas is sent into the second unstripped gas water cooler through the 12 pipeline; In the second unstripped gas water cooler, after the logistics heat exchange such as crude synthesis gas and virgin gas, middle pressure nitrogen, be divided into two strands of crude synthesis gas after going out the second unstripped gas water cooler; One crude synthesis gas gets into the first unstripped gas water cooler through the 15 pipeline; In fuel gas, SNG cool off, press nitrogen, go out the first unstripped gas water cooler after, crude synthesis gas, fuel gas, SNG etc. are all by re-heat to normal temperature; Another strand crude synthesis gas send the low-temperature rectisol step to return the cold that is brought from the low-temperature rectisol step by virgin gas; Returning the back converges with the crude synthesis gas that the first unstripped gas water cooler comes out; After accurate adjustment, be H2/N2 that 3 synthetic gas is sent into ammonia synthesis step synthetic ammonia.

(b) press the nitrogen streamline in

Get into the middle pressure nitrogen of liquid nitrogen washing step; Earlier in first feed cooler; After part crude synthesis gas, fuel gas and SNG cooling, get into the second unstripped gas water cooler through second pipeline, further cooled off by crude synthesis gas, fuel gas and SNG; After going out the second unstripped gas water cooler; Again through the 3rd pipeline send into be synthesized gas, fuel gas and SNG in the 3rd unstripped gas water cooler further cooling back form again in hydraulic fluid nitrogen, middle hydraulic fluid nitrogen separated into two parts, the top that hydraulic fluid nitrogen gets into nitrogen wash column in the part is as washings; Hydraulic fluid nitrogen isenthalpic throttling is sent into gas liquid mixer through the 11 pipeline in another part, mixes with the nitrogen gas washing that contains small amount of nitrogen after the purification of sending into gas liquid mixer through the tenth pipeline, becomes H2/N2 and be 3 crude synthesis gas.Because its differential pressure drop hanged down generation J-T effect after middle hydraulic fluid nitrogen imported the nitrogen gas washing that contains small amount of nitrogen after purifying, and provided the liquid nitrogen washing step required cold.

Perhaps go out the middle pressure nitrogen separated into two parts behind the second unstripped gas water cooler; Press in the part nitrogen through the 3rd pipeline send into be synthesized gas, fuel gas and SNG in the 3rd unstripped gas water cooler further cooling form again in hydraulic fluid nitrogen; Press the nitrogen isenthalpic throttling to send into gas gas mixing tank in another part through the 13 pipeline, with go out the 3rd unstripped gas water cooler after the crude synthesis gas that gets in the gas gas mixing tank mix.The liquid nitrogen that goes out the 3rd unstripped gas water cooler is divided into two portions, and a part of liquid nitrogen gets into the top of nitrogen wash column as washings; Another part liquid nitrogen isenthalpic throttling is sent into gas liquid mixer, mixes with the nitrogen gas washing that contains small amount of nitrogen after the purification of sending into gas liquid mixer through the tenth pipeline.Since middle hydraulic fluid nitrogen with in the low J-T of generation of its differential pressure drop effect behind the nitrogen gas washing that contains small amount of nitrogen of nitrogen after import purifying of calming the anger, provide the liquid nitrogen washing step required cold.

(c) fuel gas streamline

The fraction of discharging at the bottom of the nitrogen wash column tower is sent into flash tank through the 17 pipeline; The gas that methane rectifying tower cat head comes out is also sent into flash tank through the 18 pipeline after reducing pressure; After flash tank carries out gas-liquid separation; Gas that flash tank comes out and liquid get into the cooling of the 3rd unstripped gas water cooler through the 19 pipeline and the 20 pipeline respectively and form fuel gas; Fuel gas by the 3rd unstripped gas water cooler comes out is sent into the further heat exchange of the second unstripped gas water cooler through the 21 pipeline; Send in the first unstripped gas water cooler through the 22 pipeline and carry out re-heat, the fuel gas that goes out behind the first unstripped gas water cooler is sent to the combustion gas storage tank in the fuel gas system.In the gas-liquid separation process of flash tank, can replenish liquid nitrogen.

(d) SNG streamline

By the liquid of discharging at the bottom of the methane rectifying Tata; Get into the 3rd unstripped gas water cooler re-heat through the 24 pipeline; The liquid that the 3rd unstripped gas water cooler comes out is sent into the further re-heat of the second unstripped gas water cooler through the 25 pipeline again; The liquid that the second unstripped gas water cooler comes out is sent into the first unstripped gas water cooler re-heat to normal temperature through the 27 pipeline again, goes out the liquid nitrogen washing step.But this SNG arrives cities and towns or the SNG storage tank that needs through the compression pipe-line transportation again.

The present invention compared with prior art has following obvious characteristics:

1. the methane rectifying tower is set, uses the methane rich of liquid nitrogen washing step and form the specification that reaches SNG.Farthest reclaimed methane in the virgin gas.

2. liquid is set joins nitrogen and gas and join nitrogen and slightly join the nitrogen mode for two kinds, give full play to the efficient of water cooler.

3. the mode of methane rectifying tower tower bottom reboiler adjustable heat load is set, guarantees the SNG product specification.

4. nitrogen wash column is set, and the synthetic gas specification of using the liquid nitrogen washing step is qualified.

5. the decompression of fuel gas stream is set, cold is provided.

6. the decompression of methane-rich stream is set, cold is provided.

The present invention's ammonia synthesis gas field of purification at home develops a kind of purified synthesis gas of fixed bed crushed coal pressurized-gasification furnace and flow process that combines of low temperature separation process of being applicable to; In this flow process, need not increase any moving equipment (like decompressor or pump etc.); Can realize the coproduction of synthetic ammonia and SNG, the novel low temperature separation process and the purification techniques of low investment, less energy-consumption.The configuration of improvement flow process, by-product SNG when reaching decontamination effect improving, thus reach low effect of investing less energy-consumption high heating value high benefit.

Join methane conversion with traditional liquid nitrogen washing device and compare, apparatus of the present invention have the following advantages:

(1) plant investment is lower.Only increase a rectifying tower, the size of miscellaneous equipment such as water cooler, nitrogen wash column can remain unchanged.

(2) process cost is lower.Need not to increase the product that Purge gas institute chilling requirement just can be realized low temperature separation process SNG specification; The irreversible loss of heat transfer process has been saved in the properly distributed of cold grade and use in the liquid nitrogen washing step; Reduce the cold damage in the liquid nitrogen washing step, also just reduced the demand of empty minute feed flow nitrogen.Do not increase any moving equipment, consumption does not just increase electric power yet.

(3) the synthesic gas compressor power consumption can not increase.Though by-product the product of SNG specification, the cold in the liquid nitrogen washing step is redistributed and is utilized, and remains unchanged can guarantee that synthetic gas channel resistance in the liquid nitrogen washing step falls, and therefore can not increase consumption of compressor.

(4) product of by-product SNG specification.But the product that meets the SNG specification of by-product high heating value, methane recovery can bring up to 88%.Improve near the environment protection of the manufacturing district in life of urban resident environment and city; Solution is away from the requirement for clean fuel of the industrial and mining enterprises of neutralizing gas; Stablize natural gas supply.

(5) strict guarantee synthetic gas specification.Though by-product the product of SNG specification, do not increase extra cold again, resistance drop remains unchanged again, can guarantee that synthetic gas goes the specification of synthesis loop.

Description of drawings

Fig. 1 is existing synthetic ammonia process block diagram based on the fixed bed crushed coal pressurized-gasification furnace.

Fig. 2 is fixed bed broken coal pressing gas system ammonia synthesis gas of the present invention and SNG co-production FB(flow block).

Fig. 3 is the schematic flow sheet of the embodiment of the invention 1 liquid nitrogen washing device.

Fig. 4 is the schematic flow sheet of the embodiment of the invention 2 liquid nitrogen washing devices.

Embodiment

In order to make technique means of the present invention, creation characteristic, to reach purpose and effect and be easy to understand and understand,, further set forth the present invention below in conjunction with specific embodiment.

Referring to Fig. 2; Fixed bed broken coal pressing gas system ammonia synthesis gas and the employed device of SNG co-production; Comprise CO changing device 100, low temperature washing device for methanol 200, liquid nitrogen washing device 300, synthetic ammonia installation 400; Through seeing ammonia off behind CO changing device 100, low temperature washing device for methanol 200, liquid nitrogen washing device, the synthetic ammonia installation, characteristic of the present invention just is in liquid nitrogen washing device 300, to be provided with SNG outlet, by-product SNG to its raw gas 500 successively.Rest part and existing synthetic ammonia process based on the fixed bed crushed coal pressurized-gasification furnace are basic identical.Be elaborated with regard to liquid nitrogen washing device 300 by-product SNG below.

Embodiment 1

The flow process that embodiment 1 adopts shown in accompanying drawing 3.As can be seen from the figure, whole liquid nitrogen washing device 300 liquid nitrogen washing devices comprise unstripped gas water cooler E-01, E-02, E-03, nitrogen wash column T-01, separating tank V-01, flash tank V-02, methane rectifying tower T-02, gas liquid mixer M-02, gas gas mixing tank M-01.

The middle pressure nitrogen inlet 1 of unstripped gas water cooler E-01 connects the empty middle pressure nitrogen that divides through pipeline 2; The middle pressure nitrogen outlet 3 of unstripped gas water cooler E-01 connects the middle pressure nitrogen inlet 5 of unstripped gas water cooler E-02 through pipeline 4; The middle pressure nitrogen outlet 6 of unstripped gas water cooler E-02 connects the middle pressure nitrogen inlet 8 of unstripped gas water cooler E-03 through pipeline 7, and the liquid nitrogen outlet 9 of unstripped gas water cooler E-03 is connected to the liquid nitrogen inlet 11 on nitrogen wash column T-01 top through pipeline 10.

The virgin gas inlet 12 of unstripped gas water cooler E-02 is connected to the virgin gas outlet (not shown) of low temperature washing device for methanol through pipeline 13; The virgin gas outlet 14 of unstripped gas water cooler E-02 enters the mouth 16 through the virgin gas that pipeline 15 is connected to unstripped gas water cooler E-03, and the virgin gas outlet 17 of unstripped gas water cooler E-03 is connected to the virgin gas inlet 19 on the separating tank V-01 sidewall through pipeline 18.

The top of separating tank V-01 is provided with the virgin gas outlet 20 behind the separation of methane cut, and the bottom is provided with methane fraction liquid exit 21, and the virgin gas outlet 20 behind the separation of methane cut is connected to the virgin gas inlet 23 of nitrogen wash column T-01 bottom through pipeline 22.

Methane fraction liquid exit 21 is connected to the methane fraction inlet 25 of methane rectifying tower T-02 bottom through pipeline 24; The top of nitrogen wash column T-01 is provided with nitrogen gas washing outlet 26, and the bottom is provided with cut liquid exit 27; The top of methane rectifying tower T-02 is provided with pneumatic outlet 28, and the bottom is provided with SNG liquid exit 29.

The outlet 26 of nitrogen gas washing is connected to the inlet of gas liquid mixer M-02 through pipeline 30; The outlet of gas liquid mixer M-02 is connected to the nitrogen gas washing inlet 31 of unstripped gas water cooler E-03; On gas liquid mixer M-02, also be provided with and join nitrogen mouth 32, join nitrogen mouth 32 and be connected to pipeline 10 through pipeline 33 and throttling valve (not shown); The nitrogen gas washing outlet 34 of unstripped gas water cooler E-03 is connected to the inlet of gas gas mixing tank M-01; The outlet of gas gas mixing tank M-01 is connected to the nitrogen gas washing inlet 36 of unstripped gas water cooler E-02 through pipeline 35; On gas gas mixing tank M-01, also be provided with and join nitrogen mouth 37, join nitrogen mouth 37 and be connected to pipeline 7 through pipeline 38 and throttling valve (not shown).

The nitrogen gas washing outlet 39 of unstripped gas water cooler E-02 connects the cold synthetic gas inlet (not shown) in the low temperature washing device for methanol through pipeline 40 on the one hand; Connect the synthetic gas inlet 42 of unstripped gas water cooler E-01 on the other hand through pipeline 41, the syngas outlet 43 of unstripped gas water cooler E-01 is bonded into the hot synthesis gas inlet (not shown) of ammonia device through pipeline 44.

Hot synthesis gas outlet (not shown) in the low temperature washing device for methanol is taken over line 44; The cut liquid exit 27 of nitrogen wash column T-01 bottom is connected to the cut liquid inlet 46 on the flash tank V-02 through pipeline 45, and the pneumatic outlet 28 at methane rectifying tower T-02 top connects the gas inlet 48 on the flash tank V-02 through pipeline 47; The top of flash tank V-02 is provided with pneumatic outlet 49; The bottom is provided with liquid exit 50; The pneumatic outlet 49 at flash tank V-02 top enters the mouth 52 through the fuel gas that pipeline 51 is connected to unstripped gas water cooler E-03, and the liquid exit 50 of flash tank V-02 bottom is connected to the fuel gas inlet 52 of unstripped gas water cooler E-03 through pipeline 53.

The fuel gas outlet 54 of unstripped gas water cooler E-03 is connected to the fuel gas inlet 56 of unstripped gas water cooler E-02 through pipeline 55; The outlet 57 of the fuel gas of unstripped gas water cooler E-02 is connected to the fuel gas inlet 59 of unstripped gas water cooler E-01 through pipeline 58, and the fuel gas outlet of unstripped gas water cooler E-01 60 connects the combustion gas storage tank through pipeline 61.

The SNG liquid exit 29 of methane rectifying tower T-02 bottom is connected to the SNG inlet 63 of unstripped gas water cooler E-03 through pipeline 62; The SNG outlet 64 of unstripped gas water cooler E-03 is connected to the SNG inlet 66 of unstripped gas water cooler E-02 through pipeline 65; The SNG outlet 67 of unstripped gas water cooler E-02 is connected to the SNG inlet 69 of unstripped gas water cooler E-01 through pipeline 68; The SNG outlet 70 of unstripped gas water cooler E-01 constitutes the SNG outlet in the liquid nitrogen washing device 300, and the SNG outlet of this unstripped gas water cooler E-01 is connected to cities and towns SNG pipe network or SNG storage tank through pipeline 71.

The liquid nitrogen washing device 300 of this embodiment mainly is made up of following four streamlines:

(a) purified gas streamline

The virgin gas that comes out from low-temperature rectisol step molecular sieve gets into the liquid nitrogen washing step through pipeline 13; In unstripped gas water cooler E-02, E-03, carry out heat exchange with the synthetic gas, fuel gas and the methane rich cut (SNG) that backflow; After using virgin gas temperature behind the unstripped gas water cooler E-03 and reducing; Getting into separating tank V-01 through pipeline 18 separates the methane fraction in the virgin gas; Virgin gas behind the separation of methane cut is come out by the virgin gas outlet 20 at separating tank V-01 top, gets into the bottom of nitrogen wash column T-01 through pipeline 22.In nitrogen wash column T-01, liquid nitrogen counter current contact on nitrogen wash column T-01 column plate that the virgin gas of rising and nitrogen wash column top are come, and carry out mass transfer, heat transfer.Impurity such as CO, CH4, Ar are dissolved in the liquid nitrogen from vapor condensation, and the nitrogen gas washing that contains small amount of nitrogen after the purification leaves nitrogen wash column T-01 by the cat head of nitrogen wash column T-01, get into gas liquid mixer M-02 through pipeline 30; Mix with hydraulic fluid nitrogen in the part of sending into gas liquid mixer M-02 through 33 pipelines; Incorporate hydraulic fluid nitrogen in the part into, charging feed gas cooler E-03 re-heat again goes out unstripped gas water cooler E-03 after the re-heat; Send into gas gas mixing tank M-01 again; Mix with the middle pressure nitrogen of bringing through pipeline 38, make H2/N2 reach 3 (volume ratios) approximately, the nitrogen gas washing of joining behind the nitrogen is called crude synthesis gas.Crude synthesis gas carries out re-heat through pipeline 35 charging feed gas cooler E-02, in unstripped gas water cooler E-02, after the logistics heat exchange such as crude synthesis gas and virgin gas, middle pressure nitrogen, goes out unstripped gas water cooler E-02.The crude synthesis gas that goes out behind the unstripped gas water cooler E-02 is divided into two strands of crude synthesis gas; One crude synthesis gas is through pipeline 41 incoming stock gas cooler E-01; In fuel gas, SNG cool off, press nitrogen to carry out re-heat, the crude synthesis gas after the re-heat goes out unstripped gas water cooler E-01; Another strand crude synthesis gas send low temperature washing device for methanol 200 to return the cold that is brought from low temperature washing device for methanol 200 by virgin gas; Returning the back converges with the crude synthesis gas that unstripped gas water cooler E-01 comes out; After accurate adjustment, be H2/N2 that 3 synthetic gas is sent into ammonia synthesizer 400 synthetic ammonia.

(b) press the nitrogen streamline in

Get into the middle pressure nitrogen of liquid nitrogen washing device 300 through pipeline 2; Earlier in feed cooler E-01; After part crude synthesis gas, fuel gas and SNG cooling; Through pipeline 4 incoming stock gas cooler E-02; Further cooled off by crude synthesis gas, fuel gas and SNG, go out the middle pressure nitrogen separated into two parts behind the unstripped gas water cooler E-02, press nitrogen in the part through hydraulic fluid nitrogen in being synthesized gas, fuel gas and SNG among the pipeline 7 charging feed gas cooler E-03 further cooling forming again; Press the nitrogen isenthalpic throttling to send into gas gas mixing tank M-01 in another part through pipeline 38, with go out unstripped gas water cooler E-03 after the crude synthesis gas that gets among the gas gas mixing tank M-01 mix.The liquid nitrogen that goes out unstripped gas water cooler E-03 is divided into two portions, and a part of liquid nitrogen passes through the top of pipeline 10 entering nitrogen wash column T-01 as washings; Another part liquid nitrogen isenthalpic throttling is sent into gas liquid mixer M-02 through pipeline 33, mixes with the nitrogen gas washing that contains small amount of nitrogen after the purification of sending into gas liquid mixer M-02 through pipeline 30.Since middle hydraulic fluid nitrogen with in the low J-T of generation of its differential pressure drop effect behind the nitrogen gas washing that contains small amount of nitrogen of nitrogen after import purifying of calming the anger, provide the liquid nitrogen washing step required cold.

(c) fuel gas streamline

The fraction of discharging at the bottom of the nitrogen wash column T-01 tower is sent into flash tank V-02 through pipeline 45; The gas that methane rectifying tower T-02 cat head comes out is also sent into flash tank V-02 through pipeline 47 after reducing pressure; After flash tank V-02 carries out gas-liquid separation; Gas that flash tank V-02 comes out and liquid are respectively through forming fuel gas after pipeline 51, the 53 incoming stock gas cooler E-03 re-heats; The fuel gas that is come out by unstripped gas water cooler E-03 passes through the further re-heat of pipeline 55 charging feed gas cooler E-02; Again through carrying out re-heat among the pipeline 58 charging feed gas cooler E-01, the fuel gas that goes out behind the unstripped gas water cooler E-01 is sent to the combustion gas storage tank in the fuel gas system.

(d) SNG streamline

By the liquid of discharging at the bottom of the methane rectifying tower T-02 tower; Through pipeline 62 incoming stock gas cooler E-03 re-heats; The liquid that unstripped gas water cooler E-03 comes out is again through the further re-heat of pipeline 65 charging feed gas cooler E-02; The liquid that unstripped gas water cooler E-02 comes out passes through pipeline 68 charging feed gas cooler E-01 re-heats again to normal temperature, goes out liquid nitrogen cleaning device 300.The methane content that goes out liquid nitrogen cleaning device 300 is 95% (mol), and CO＜1000ppmv can be used as SNG and uses after pressurization.

Be provided with reboiler 72 at the bottom of the tower of methane rectifying tower T-02, the inlet connection line 14 of reboiler 72 or pipeline 6 insert virgin gas or middle pressure nitrogen, the downstream end line 15 of reboiler 72 or pipeline 7.The mode of reboiler 72 adjustable heat load is set at the bottom of the methane rectifying tower T-02 tower, guarantees the SNG product specification.

Present embodiment is 101490Nm3/h for raw gas flow, pressure 4.7MPa (G), and synthetic ammonia output is 1050MTPD, and the amount of by-product SNG is 5,700 ten thousand Nm3/y, and methane content is 95% (mol), CO＜1000ppmv, the recovery is about 88%.As as gas usefulness, will have the benefit of 1.425 hundred million Renminbi every year.

Embodiment 2

The flow process that embodiment 2 adopts shown in accompanying drawing 4.As can be seen from the figure, whole liquid nitrogen washing device 300 liquid nitrogen washing devices comprise unstripped gas water cooler E-01, E-02, E-03, nitrogen wash column T-01, separating tank V-01, flash tank v-02, methane rectifying tower T-02, gas liquid mixer M-02.

The outlet 26 of nitrogen gas washing is connected to the inlet of gas liquid mixer M-02 through pipeline 30; The outlet of gas liquid mixer M-02 is connected to the nitrogen gas washing inlet 31 of unstripped gas water cooler E-03; On gas liquid mixer M-02, also be provided with and join nitrogen mouth 32, join nitrogen mouth 32 and be connected to pipeline 10 through pipeline 33 and throttling valve (not shown); The nitrogen gas washing outlet 34 of unstripped gas water cooler E-03 is connected to the nitrogen gas washing inlet 36 of unstripped gas water cooler E-02 through pipeline 35.

Hot synthesis gas outlet (not shown) in the low temperature washing device for methanol is taken over line 44; The cut liquid exit 27 of nitrogen wash column T-01 bottom is connected to the cut liquid inlet 46 on the flash tank V-02 through pipeline 45, and the pneumatic outlet 28 at methane rectifying tower T-02 top connects the gas inlet 48 on the flash tank V-02 through pipeline 47; The top of flash tank V-02 is provided with pneumatic outlet 49, and the bottom is provided with liquid exit 50, and sidewall is provided with mends nitrogen mouth 73.The pneumatic outlet 49 at flash tank V-02 top enters the mouth 52 through the fuel gas that pipeline 51 is connected to unstripped gas water cooler E-03, and the liquid exit 50 of flash tank V-02 bottom is connected to the fuel gas inlet 52 of unstripped gas water cooler E-03 through pipeline 53.Mend nitrogen mouth 73 and be connected to pipeline 44 through pipeline 74.

(a) purified gas streamline

The virgin gas that comes out from low-temperature rectisol step molecular sieve gets into the liquid nitrogen washing step through pipeline 13; In unstripped gas water cooler E-02, E-03, carry out heat exchange with the synthetic gas, fuel gas and the methane rich cut (SNG) that backflow; After using virgin gas temperature behind the unstripped gas water cooler E-03 and reducing; Getting into separating tank V-01 through pipeline 18 separates the methane fraction in the virgin gas; Virgin gas behind the separation of methane cut is come out by the virgin gas outlet 20 at separating tank V-01 top, gets into the bottom of nitrogen wash column T-01 through pipeline 22.In nitrogen wash column T-01, liquid nitrogen counter current contact on nitrogen wash column T-01 column plate that the virgin gas of rising and nitrogen wash column top are come, and carry out mass transfer, heat transfer.Impurity such as CO, CH4, Ar are dissolved in the liquid nitrogen from vapor condensation; The nitrogen gas washing that contains small amount of nitrogen after the purification leaves nitrogen wash column T-01 by the cat head of nitrogen wash column T-01; Get into gas liquid mixer M-02 through pipeline 30, mix, incorporate hydraulic fluid nitrogen in the part into hydraulic fluid nitrogen in the part of sending into gas liquid mixer M-02 through 33 pipelines; Make H2/N2 reach 3 (volume ratios) approximately, the nitrogen gas washing of joining behind the nitrogen is called crude synthesis gas.Crude synthesis gas carries out re-heat through pipeline 35 charging feed gas cooler E-02, in unstripped gas water cooler E-02, after the logistics heat exchange such as crude synthesis gas and virgin gas, middle pressure nitrogen, goes out unstripped gas water cooler E-02.The crude synthesis gas that goes out behind the unstripped gas water cooler E-02 is divided into two strands of crude synthesis gas; One crude synthesis gas is through pipeline 41 incoming stock gas cooler E-01; In fuel gas, SNG cool off, press nitrogen to carry out re-heat, the crude synthesis gas after the re-heat goes out unstripped gas water cooler E-01; Another strand crude synthesis gas send low temperature washing device for methanol 200 to return the cold that is brought from low temperature washing device for methanol 200 by virgin gas; Returning the back converges with the crude synthesis gas that unstripped gas water cooler E-01 comes out; After accurate adjustment, be H2/N2 that 3 synthetic gas is sent into ammonia synthesizer 400 synthetic ammonia.

(b) press the nitrogen streamline in

Get into the middle pressure nitrogen of liquid nitrogen washing device 300 through pipeline 2; Earlier in feed cooler E-01; After part crude synthesis gas, fuel gas and SNG cooling; Through pipeline 4 incoming stock gas cooler E-02, further cooled off by crude synthesis gas, fuel gas and SNG, go out middle pressure nitrogen behind the unstripped gas water cooler E-02 through hydraulic fluid nitrogen in being synthesized gas, fuel gas and SNG among the pipeline 7 charging feed gas cooler E-03 further cooling forming again.The liquid nitrogen that goes out unstripped gas water cooler E-03 is divided into two portions, and a part of liquid nitrogen passes through the top of pipeline 10 entering nitrogen wash column T-01 as washings; Another part liquid nitrogen isenthalpic throttling is sent into gas liquid mixer M-02 through pipeline 33, mixes with the nitrogen gas washing that contains small amount of nitrogen after the purification of sending into gas liquid mixer M-02 through pipeline 30.Because its differential pressure drop hanged down generation J-T effect after middle hydraulic fluid nitrogen imported the nitrogen gas washing that contains small amount of nitrogen after purifying, and provided the liquid nitrogen washing step required cold.

(c) fuel gas streamline

(d) SNG streamline

Present embodiment is 101289Nm3/h for raw gas flow, pressure 3.2MPa (G), and synthetic ammonia output is 1050MTPD, and the amount of by-product SNG is 5,698 ten thousand Nm3/y, and methane content is 95% (mol), CO＜1000ppmv, the recovery is about 88%.As as gas usefulness, will have the benefit of 1.425 hundred million Renminbi every year.

More than show and described ultimate principle of the present invention, principal character and advantage of the present invention.The technician of the industry should understand; The present invention is not restricted to the described embodiments; That describes in the foregoing description and the specification sheets just explains principle of the present invention; The present invention also has various changes and modifications under the prerequisite that does not break away from spirit and scope of the invention, and these variations and improvement all fall in the scope of the invention that requires protection.The present invention requires protection domain to be defined by appending claims and equivalent thereof.

Claims

1. fixed bed broken coal pressing gas system ammonia synthesis gas and SNG co-production after its raw gas process CO shift step, low-temperature rectisol step, the liquid nitrogen washing step, are sent into synthetic ammonia step synthetic ammonia, it is characterized in that, tell SNG in said liquid nitrogen washing step.

2. fixed bed broken coal pressing gas system ammonia synthesis gas as claimed in claim 1 and SNG co-production; It is characterized in that; Said liquid nitrogen washing step comprises that cooling step, methane separation step, nitrogen washes step, methane rectification step, gas-liquid separation step; The virgin gas of being come by the low-temperature rectisol step is after said cooling step heat exchange; Send into said methane separation step and carry out the methane fraction separation, the virgin gas A behind the said methane separation step separation of methane cut sends into nitrogen and washes step, and the isolating methane fraction of methane separation step is sent into the methane rectification step and carried out rectifying; The middle pressure nitrogen that gets into the liquid nitrogen washing step forms liquid nitrogen and sends into nitrogen and wash step after said cooling step heat exchange; With send into nitrogen and wash the virgin gas A counter current contact of step; And carry out mass transfer, heat transfer; CO among the virgin gas A, CH4, Ar impurity are dissolved in the liquid nitrogen from vapor condensation; The nitrogen gas washing that contains small amount of nitrogen that said nitrogen is washed after the step purge is sent into said cooling step; Said nitrogen is washed step cut that comes out and the gas B entering gas-liquid separation step of being come out by said methane rectification step and is carried out gas-liquid separation; Said gas-liquid separation step gas separated C and liquid B are sent into said cooling step respectively; The liquid A that said methane rectification step is come out is sent into said cooling step, send into nitrogen gas washing, gas C, liquid A, the liquid B of said cooling step and send into the virgin gas in the cooling step, middle pressure nitrogen carries out heat exchange, form synthetic gas after wherein said nitrogen is washed the nitrogen gas washing that contains small amount of nitrogen after the step purge and in said cooling step, joined nitrogen and send into the synthetic ammonia step; The liquid A that said methane rectification step is come out is seen off through forming SNG after the heat exchange, and said gas-liquid separation step gas separated C and liquid B are mixed after heat exchange formation fuel gas is seen off at said cooling step.

3. fixed bed broken coal pressing gas system ammonia synthesis gas as claimed in claim 2 and SNG co-production; It is characterized in that; Said cooling step is divided into first cooling step, second cooling step, the 3rd cooling step; The middle pressure nitrogen of said entering liquid nitrogen washing step is sent into nitrogen through formation liquid nitrogen after first cooling step, second cooling step, the 3rd cooling step heat exchange successively and is washed step; Said virgin gas of being come by the low-temperature rectisol step is sent into said methane separation step and is carried out the methane fraction separation successively through after second cooling step, the 3rd cooling step heat exchange; The nitrogen gas washing that contains small amount of nitrogen that said nitrogen is washed after the step purge is sent into the 3rd cooling step behind the nitrogen and is carried out heat exchange through joining for the first time; Send into second cooling step again through the nitrogen gas washing after the 3rd cooling step heat exchange and carry out heat exchange formation crude synthesis gas; Crude synthesis gas after the second cooling step heat exchange is divided into two strands; Wherein first strand of crude synthesis gas sent into first cooling step and carried out heat exchange; Form the crude synthesis gas of normal temperature; Second strand of crude synthesis gas send the low-temperature rectisol step to return the cold that is brought from the low-temperature rectisol step by Purge gas, and the crude synthesis gas of the normal temperature that comes out with first cooling step after returning converges through accurate adjustment formation synthetic gas sends into synthetic ammonia step synthetic ammonia; The liquid A that said methane rectification step is come out is seen off through the SNG that forms normal temperature after the 3rd cooling step, second cooling step, the first cooling step heat exchange successively; After said gas-liquid separation step gas separated C and liquid B are mixed in the 3rd cooling step, see off through the fuel gas that forms normal temperature after second cooling step, the first cooling step heat exchange successively again.

4. fixed bed broken coal pressing gas system ammonia synthesis gas as claimed in claim 3 and SNG co-production is characterized in that, in said gas-liquid separation step, also replenish liquid nitrogen.

5. fixed bed broken coal pressing gas system ammonia synthesis gas as claimed in claim 3 and SNG co-production; It is characterized in that, send into second cooling step behind the nitrogen again and carry out heat exchange and form crude synthesis gas through joining for the second time through the nitrogen gas washing after the 3rd cooling step heat exchange.

6. fixed bed broken coal pressing gas system ammonia synthesis gas as claimed in claim 4 and SNG co-production; It is characterized in that; Said nitrogen is washed the nitrogen gas washing that contains small amount of nitrogen after the step purge and is joined the liquid nitrogen that the nitrogenous source of nitrogen is hung oneself and come out after the 3rd cooling step heat exchange for the first time, and said nitrogen is washed the nitrogen gas washing that contains small amount of nitrogen after the step purge and joined the middle pressure nitrogen that nitrogen is hung oneself and come out after the second cooling step heat exchange for the second time.

7. fixed bed broken coal pressing gas system ammonia synthesis gas as claimed in claim 6 and SNG co-production is characterized in that, the nitrogenous source of joining nitrogen the said first time adopts the isenthalpic throttling mode to allocate in the nitrogen gas washing that contains small amount of nitrogen after said nitrogen is washed step purge.

8. fixed bed broken coal pressing gas system ammonia synthesis gas as claimed in claim 3 and SNG co-production is characterized in that, the nitrogenous source of joining nitrogen the said second time adopts the isenthalpic throttling mode to allocate in the nitrogen gas washing that contains small amount of nitrogen after said nitrogen is washed step purge.

9. the described fixed bed broken coal of claim 1 pressing gas system ammonia synthesis gas and the employed device of SNG co-production; Comprise CO changing device, low temperature washing device for methanol, liquid nitrogen washing device, synthetic ammonia installation; Its raw gas is successively through seeing ammonia off behind CO changing device, low temperature washing device for methanol, liquid nitrogen washing device, the synthetic ammonia installation; It is characterized in that, in said liquid nitrogen washing device, be provided with the SNG outlet.

10. device as claimed in claim 9; It is characterized in that said liquid nitrogen washing device comprises the first unstripped gas water cooler, the second unstripped gas water cooler, the 3rd unstripped gas water cooler, nitrogen wash column, separating tank, flash tank, methane rectifying tower, gas liquid mixer, gas gas mixing tank; The middle pressure nitrogen inlet of the said first unstripped gas water cooler connects the empty middle pressure nitrogen that divides through first pipeline; The middle pressure nitrogen outlet of the first unstripped gas water cooler connects the middle pressure nitrogen inlet of the said second unstripped gas water cooler through second pipeline; The middle pressure nitrogen outlet of the said second unstripped gas water cooler connects the middle pressure nitrogen inlet of said the 3rd unstripped gas water cooler through the 3rd pipeline, and the liquid nitrogen outlet of the 3rd unstripped gas water cooler is connected to the liquid nitrogen inlet on said nitrogen wash column top through the 4th pipeline; The virgin gas inlet of the said second unstripped gas water cooler is connected to the virgin gas outlet of said low temperature washing device for methanol through the 5th pipeline; The virgin gas outlet of the second unstripped gas water cooler enters the mouth through the virgin gas that the 6th pipeline is connected to said the 3rd unstripped gas water cooler, and the virgin gas outlet of the 3rd unstripped gas water cooler is connected to the virgin gas inlet on the separating tank sidewall through the 7th pipeline; The top of said separating tank is provided with the virgin gas outlet behind the separation of methane cut; The bottom of separating tank is provided with the methane fraction liquid exit; Virgin gas outlet behind the said separation of methane cut enters the mouth through the virgin gas that the 8th pipeline is connected to said nitrogen wash column bottom, and said methane fraction liquid exit is connected to the methane fraction inlet of said methane rectifying tower bottom through the 9th pipeline; The top of said nitrogen wash column is provided with the outlet of nitrogen gas washing, and the bottom of nitrogen wash column is provided with the cut liquid exit; The top of said methane rectifying tower is provided with pneumatic outlet, and the bottom of methane rectifying tower is provided with the SNG liquid exit; Said nitrogen gas washing outlet is connected to the inlet of said gas liquid mixer through the tenth pipe; The outlet of said gas liquid mixer is connected to the nitrogen gas washing inlet of the 3rd unstripped gas water cooler; On said gas liquid mixer, also be provided with first and join the nitrogen mouth, said first joins the nitrogen mouth is connected to said the 4th pipeline through the 11 pipeline and first throttle valve; The nitrogen gas washing outlet of the 3rd unstripped gas water cooler is connected to the inlet of said gas gas mixing tank; The outlet of gas gas mixing tank is connected to the nitrogen gas washing inlet of the said second unstripped gas water cooler through the 12 pipeline; On said gas gas mixing tank, also be provided with second and join the nitrogen mouth, said second joins the nitrogen mouth is connected to said the 3rd pipeline through the 13 pipeline and second throttling valve; The nitrogen gas washing outlet of the said second unstripped gas water cooler connects the cold synthetic gas inlet in the said low temperature washing device for methanol through the 14 pipeline on the one hand; The nitrogen gas washing outlet of the second unstripped gas water cooler connects the synthetic gas inlet of the said first unstripped gas water cooler on the other hand through the 15 pipeline; The syngas outlet of the first unstripped gas water cooler enters the mouth through the hot synthesis gas that the 16 pipeline is bonded into ammonia device, and the hot synthesis gas outlet in the said low temperature washing device for methanol connects the 16 pipeline; The cut liquid exit of said nitrogen wash column bottom is connected to the cut liquid inlet on the said flash tank through the 17 pipeline, and the pneumatic outlet at said methane rectifying tower top connects the gas inlet on the said flash tank through the 18 pipeline; The top of said flash tank is provided with pneumatic outlet; The bottom of flash tank is provided with liquid exit; The pneumatic outlet of said flash drum overhead is connected to the fuel gas inlet of said the 3rd unstripped gas water cooler through the 19 pipeline; The liquid exit of flash tank bottom is connected to the fuel gas inlet of said the 3rd unstripped gas water cooler through the 20 pipeline; The fuel gas outlet of said the 3rd unstripped gas water cooler is connected to the fuel gas inlet of the said second unstripped gas water cooler through the 21 pipeline; The fuel gas outlet of the second unstripped gas water cooler enters the mouth through the fuel gas that the 22 pipeline is connected to the said first unstripped gas water cooler, and the fuel gas outlet of the first unstripped gas water cooler is connected to the fuel gas storage tank through the 23 pipeline; The SNG liquid exit of said methane rectifier bottoms is connected to the SNG inlet of said the 3rd unstripped gas water cooler through the 24 pipeline; The SNG outlet of the 3rd unstripped gas water cooler is connected to the SNG inlet of the said second unstripped gas water cooler through the 25 pipeline; The SNG outlet of the second unstripped gas water cooler is connected to the SNG inlet of the said first unstripped gas water cooler through the 26 pipeline; SNG outlet in the said liquid nitrogen washing device of the SNG export mixes of the first unstripped gas water cooler, the SNG outlet of this first unstripped gas water cooler is connected to the SNG storage tank through the 27 pipeline.

11. device as claimed in claim 9; It is characterized in that said liquid nitrogen washing device comprises the first unstripped gas water cooler, the second unstripped gas water cooler, the 3rd unstripped gas water cooler, nitrogen wash column, separating tank, flash tank, methane rectifying tower, gas liquid mixer; The middle pressure nitrogen inlet of the said first unstripped gas water cooler connects the empty middle pressure nitrogen that divides through first pipeline; The middle pressure nitrogen outlet of the first unstripped gas water cooler connects the middle pressure nitrogen inlet of the said second unstripped gas water cooler through second pipeline; The middle pressure nitrogen outlet of the said second unstripped gas water cooler connects the middle pressure nitrogen inlet of said the 3rd unstripped gas water cooler through the 3rd pipeline, and the liquid nitrogen outlet of the 3rd unstripped gas water cooler is connected to the liquid nitrogen inlet on said nitrogen wash column top through the 4th pipeline; The virgin gas inlet of the said second unstripped gas water cooler is connected to the virgin gas outlet of said low temperature washing device for methanol through the 5th pipeline; The virgin gas outlet of the second unstripped gas water cooler enters the mouth through the virgin gas that the 6th pipeline is connected to said the 3rd unstripped gas water cooler, and the virgin gas outlet of the 3rd unstripped gas water cooler is connected to the virgin gas inlet on the separating tank sidewall through the 7th pipeline; The top of said separating tank is provided with the virgin gas outlet behind the separation of methane cut; The bottom of separating tank is provided with the methane fraction liquid exit; Virgin gas outlet behind the said separation of methane cut enters the mouth through the virgin gas that the 8th pipeline is connected to said nitrogen wash column bottom, and said methane fraction liquid exit is connected to the methane fraction inlet of said methane rectifying tower bottom through the 9th pipeline; The top of said nitrogen wash column is provided with the outlet of nitrogen gas washing, and the bottom of nitrogen wash column is provided with the cut liquid exit; The top of said methane rectifying tower is provided with pneumatic outlet, and the bottom of methane rectifying tower is provided with the SNG liquid exit; Said nitrogen gas washing outlet is connected to the inlet of said gas liquid mixer through the tenth pipe; The outlet of said gas liquid mixer is connected to the nitrogen gas washing inlet of the 3rd unstripped gas water cooler; On said gas liquid mixer, also be provided with first and join the nitrogen mouth, said first joins the nitrogen mouth is connected to said the 4th pipeline through the 11 pipeline and first throttle valve; The nitrogen gas washing outlet of the 3rd unstripped gas water cooler is connected to the nitrogen gas washing inlet of the said second unstripped gas water cooler through the 12 pipeline; The inlet of said gas gas mixing tank, the outlet of gas gas mixing tank also is provided with second and joins the nitrogen mouth on said gas gas mixing tank, and said second joins the nitrogen mouth is connected to said the 3rd pipeline through the 13 pipeline and second throttling valve; The nitrogen gas washing outlet of the said second unstripped gas water cooler connects the cold synthetic gas inlet in the said low temperature washing device for methanol through the 14 pipeline on the one hand; The nitrogen gas washing outlet of the second unstripped gas water cooler connects the synthetic gas inlet of the said first unstripped gas water cooler on the other hand through the 15 pipeline; The syngas outlet of the first unstripped gas water cooler enters the mouth through the hot synthesis gas that the 16 pipeline is bonded into ammonia device, and the hot synthesis gas outlet in the said low temperature washing device for methanol connects the 16 pipeline; The cut liquid exit of said nitrogen wash column bottom is connected to the cut liquid inlet on the said flash tank through the 17 pipeline, and the pneumatic outlet at said methane rectifying tower top connects the gas inlet on the said flash tank through the 18 pipeline; The top of said flash tank is provided with pneumatic outlet; The bottom of flash tank is provided with liquid exit; The sidepiece of flash tank is provided with the liquid nitrogen inlet; The liquid nitrogen inlet of said flash tank sidepiece is connected to the 4th pipeline through the 24 pipeline; The pneumatic outlet of said flash drum overhead is connected to the fuel gas inlet of said the 3rd unstripped gas water cooler through the 19 pipeline; The liquid exit of flash tank bottom is connected to the fuel gas inlet of said the 3rd unstripped gas water cooler through the 20 pipeline; The fuel gas outlet of said the 3rd unstripped gas water cooler enters the mouth through the fuel gas that the 21 pipeline is connected to the said second unstripped gas water cooler, and the fuel gas outlet of the second unstripped gas water cooler enters the mouth through the fuel gas that the 22 pipeline is connected to the said first unstripped gas water cooler, and the fuel gas outlet of the first unstripped gas water cooler is connected to the fuel gas storage tank through the 23 pipeline; The SNG liquid exit of said methane rectifier bottoms is connected to the SNG inlet of said the 3rd unstripped gas water cooler through the 24 pipeline; The SNG outlet of the 3rd unstripped gas water cooler is connected to the SNG inlet of the said second unstripped gas water cooler through the 25 pipeline; The SNG outlet of the second unstripped gas water cooler is connected to the SNG inlet of the said first unstripped gas water cooler through the 26 pipeline; SNG outlet in the said liquid nitrogen washing device of the SNG export mixes of the first unstripped gas water cooler, the SNG outlet of this first unstripped gas water cooler is connected to the SNG storage tank through the 27 pipeline.

12., it is characterized in that be provided with reboiler at the bottom of the tower of said methane rectifying tower, the inlet of said reboiler connects the 3rd pipeline or the 6th pipeline like claim 10 or 11 described devices, the outlet of reboiler takes back the 3rd pipeline or the 6th pipeline.